The present invention relates to a wiper motor for vehicles, more particularly to an air-cooled wiper motor provided with a self-cooling fan.
Recently, parts for vehicles, particularly for automobiles are tried to be light in weight viewed from economy of fuel, material or the like, while a wiper blade tends to be large for the purpose of obtaining the good field of vision during driving. Therefore, the power output of a wiper motor is getting larger, and the wiper motor becomes inevitably large, but such phenomenon is against a tendency of light weight.
On the other hand, as means for making the motor light or increasing only the power output with the same motor, it has been known to cool the motor with a fan. In this case, the fan is roughly divided into the following types, that is, an open type (which passes a cooling air into the motor) and a totally-enclosed type (which passes a cooling air to the outside of the sealed motor), according to use. Among these types, in case of the totally-enclosed type, in general, a ventilation cover is concentrically provided around the outer periphery of a motor to form an annular ventilation duct between the ventilation cover and the outer periphery of the motor, so that an outer diameter of the motor inclusive of the ventilation cover becomes large as a whole. In recent automobiles, piping for a brake master, cable for an automatic speed control device or the like is arranged close to a wiper motor (refer to symbol A in FIG. 2), so that it is necessary to secure the wiper motor in a fairly narrow space, and thus it is difficult to make an outer diameter of the wiper motor large in order to form a vantilation duct for cooling the wiper motor.
While an increase of the power output of the wiper motor is tried by securing a self-cooling fan to the armature shaft of the wiper motor without enlarging the wiper motor itself.
On the other hand, in the conventional wiper motor, a deceleration gear mechanism portion of a worm is provided at one end of the armature shaft, a wiper blade is reciprocally swung, and a thrust load received by the armature shaft by the deceleration gear mechanism portion is supported on the other end of the armature shaft. However, because of an increased power output of the wiper motor, when securing the self-cooling fan on the other end of the armature shaft, the construction for supporting the thrust load becomes complicated in the conventional case and assembling workability becomes lowered.